The use of oral fluid for therapeutic drug management: clinical and forensic toxicology

Can we Predict Drug Excretion into Saliva? A Systematic Review and Analysis of Physicochemical Properties

BACKGROUND AND OBJECTIVES

Saliva is a patient-friendly matrix for therapeutic drug monitoring (TDM) but is infrequently used in routine care. This is due to the uncertainty of saliva-based TDM results to inform dosing. This study aimed to retrieve data on saliva-plasma concentration and subsequently determine the physicochemical properties that influence the excretion of drugs into saliva to increase the foundational knowledge underpinning saliva-based TDM.

METHODS

Medline, Web of Science and Embase (1974-2023) were searched for human clinical studies, which determined drug pharmacokinetics in both saliva and plasma. Studies with at least ten subjects and five paired saliva-plasma concentrations per subject were included. For each study, the ratio of the area under the concentration-time curve between saliva and plasma was determined to assess excretion into saliva. Physicochemical properties of each drug (e.g. pKa, lipophilicity, molecular weight, polar surface area, rotatable bonds and fraction of drug unbound to plasma proteins) were obtained from PubChem and Drugbank. Drugs were categorised by their ionisability, after which saliva-to-plasma ratios were predicted with adjustment for protein binding and physiological pH via the Henderson-Hasselbalch equation. Spearman correlation analyses were performed for each drug category to identify factors predicting saliva excretion (α = 5%). Study quality was assessed by the risk of bias in non-randomised studies of interventions tool.

RESULTS

Overall, 42 studies including 40 drugs (anti-psychotics, anti-microbials, immunosuppressants, anti-thrombotic, anti-cancer and cardiac drugs) were included. The median saliva-to-plasma ratios were similar for drugs in the amphoteric (0.59), basic (0.43) and acidic (0.41) groups and lowest for drugs in the neutral group (0.21). Higher excretion of acidic drugs (n = 5) into saliva was associated with lower ionisation and protein binding (correlation between predicted versus observed saliva-to-plasma ratios: R2 = 0.85, p = 0.02). For basic drugs (n = 21), pKa predicted saliva excretion (Spearman correlation coefficient: R = 0.53, p = 0.02). For amphoteric drugs (n = 10), hydrogen bond donor (R = - 0.76, p = 0.01) and polar surface area (R = - 0.69, p = 0.02) were predictors. For neutral drugs (n = 10), protein binding (R = 0.84, p = 0.004), lipophilicity (R = - 0.65, p = 0.04) and hydrogen bond donor count (R = - 0.68, p = 0.03) were predictors. Drugs considered potentially suitable for saliva-based TDM are phenytoin, tacrolimus, voriconazole and lamotrigine. The studies had a low-to-moderate risk of bias.

CONCLUSIONS

Many commonly used drugs are excreted into saliva, which can be partly predicted by a drug's ionisation state, protein binding, lipophilicity, hydrogen bond donor count and polar surface area. The contribution of drug transporters and physiological factors to the excretion needs to be evaluated. Continued research on drugs potentially suitable for saliva-based TDM will aid in adopting this person-centred TDM approach to improve patient outcomes.

Levels of Bisphenol A and its analogs in nails, saliva, and urine of children: a case control study

Introduction

A growing number of studies link the increase in overweight/obesity worldwide to exposure to certain environmental chemical pollutants that display obesogenic activity (obesogens). Since exposure to obesogens during the first stages of life has been shown to have a more intense and pronounced effect at lower doses, it is imperative to study their possible effects in childhood. The objective here was to study the association of Bisphenol A (BPA) and 11 BPA analogs in children, using three biological matrices (nails, saliva and urine), and overweight and obesity (n = 160).

Methods

In this case-control study, 59 overweight/obese children and 101 controls were included. The measuring of Bisphenols in the matrices was carried out by ultra-high performance liquid chromatography coupled with triple quadrupole tandem mass spectrometry (UHPLC-MS/MS). Logistic regression was used to study the association between overweight/obesity and Bisphenol exposure.

Results

The results suggested that BPF in nails is associated with overweight/ obesity in children (OR:4.87; p = 0.020). In saliva, however, the highest detected concentrations of BPAF presented an inverse association (OR: 0.06; p = 0.010) with overweight/obesity. No associations of statistical significance were detected between exposure to BPA or its other analogs and overweight/obesity in any of the biological matrices.

Biological Fluid Microsampling for Therapeutic Drug Monitoring: A Narrative Review

Therapeutic drug monitoring (TDM) is a specialized area of laboratory medicine which involves the measurement of drug concentrations in biological fluids with the aim of optimizing efficacy and reducing side effects, possibly modifying the drug dose to keep the plasma concentration within the therapeutic range. Plasma and/or whole blood, usually obtained by venipuncture, are the "gold standard" matrices for TDM. Microsampling, commonly used for newborn screening, could also be a convenient alternative to traditional sampling techniques for pharmacokinetics (PK) studies and TDM, helping to overcome practical problems and offering less invasive options to patients. Although technical limitations have hampered the use of microsampling in these fields, innovative techniques such as 3-D dried blood spheroids, volumetric absorptive microsampling (VAMS), dried plasma spots (DPS), and various microfluidic devices (MDS) can now offer reliable alternatives to traditional samples. The application of microsampling in routine clinical pharmacology is also hampered by the need for instrumentation capable of quantifying analytes in small volumes with sufficient sensitivity. The combination of microsampling with high-sensitivity analytical techniques, such as liquid chromatography coupled with tandem mass spectrometry (LC-MS/MS), is particularly effective in ensuring high accuracy and sensitivity from very small sample volumes. This manuscript provides a critical review of the currently available microsampling devices for both whole blood and other biological fluids, such as plasma, urine, breast milk, and saliva. The purpose is to provide useful information in the scientific community to laboratory personnel, clinicians, and researchers interested in implementing the use of microsampling in their routine clinical practice.

Monitoring Salivary Concentrations of Tedizolid and Linezolid Using Rats

BACKGROUND AND OBJECTIVE

Therapeutic drug monitoring (TDM) is an effective tool for the management of patients who are administered linezolid. The use of saliva for TDM has potential advantages over the use of plasma; however, only a few reports have compared drug concentrations in the saliva and plasma. Moreover, there are no reports on the salivary concentration of tedizolid, an oxazolidinone antibiotic similar to linezolid. In the present study, the concentrations of tedizolid and linezolid in rat submandibular saliva were compared with those measured in the plasma.

METHODS

Tedizolid (10 mg/kg, n = 6) and linezolid (12 mg/kg, n = 5) were administered via the rat tail vein. Submandibular saliva and plasma samples were collected for up to 8 h after the initiation of drug administration, and assayed for the concentrations of tedizolid and linezolid.

RESULTS

A strong correlation was found between the saliva and plasma concentrations of tedizolid (r = 0.964, p < 0.001) and linezolid (r = 0.936, p < 0.001). The value of tedizolid maximum concentration of drug (C_max) was 0.99 ± 0.08 µg/mL in the saliva and 14.46 ± 1.71 µg/mL in the plasma. Meanwhile, the C_max of linezolid was 8.01 ± 1.42 µg/mL in the saliva and 13.00 ± 1.90 µg/mL in the plasma. According to these results, the saliva/plasma concentration ratios of tedizolid and linezolid in rats were 0.0513 ± 0.0080 and 0.6341 ± 0.0339, respectively.

CONCLUSIONS

Considering the correlation between saliva and plasma concentrations of tedizolid and linezolid, as well as the characteristics of saliva, the results of this study suggest that saliva is a useful matrix for TDM.

High-performance liquid chromatography with fluorescence detection for mycophenolic acid determination in saliva samples

BACKGROUND

For therapeutic drug monitoring (TDM) of mycophenolic acid (MPA), which is frequently proposed, saliva might be a suitable and easy-to-obtain biological matrix. The study aimed to validate an HPLC method with fluorescence detection for determining mycophenolic acid in saliva (sMPA) in children with nephrotic syndrome.

METHODS

The mobile phase was composed of methanol and tetrabutylammonium bromide with disodium hydrogen phosphate (pH 8.5) at a 48:52 ratio. To prepare the saliva samples, 100 µL of saliva, 50 µL of calibration standards, and 50 µL of levofloxacin (used as an internal standard) were mixed and evaporated to dryness at 45 °C for 2 h. The resulting dry extract was reconstituted in the mobile phase and injected into the HPLC system after centrifugation. Saliva samples from study participants were collected using Salivette^® devices.

RESULTS

The method was linear within the range of 5-2000 ng/mL, was selective with no carry-over effect and met the acceptance criteria for within-run and between-run accuracy and precision. Saliva samples can be stored for up to 2 h at room temperature, for up to 4 h at 4 °C, and for up to 6 months at - 80 °C. MPA was stable in saliva after three freeze-thaw cycles, in dry extract for 20 h at 4 °C, and for 4 h in the autosampler at room temperature. MPA recovery from Salivette^® cotton swabs was within the range of 94-105%. The sMPA concentrations in the two children with nephrotic syndrome who were treated with mycophenolate mofetil were within 5-112 ng/mL.

CONCLUSIONS

The sMPA determination method is specific, selective, and meets the validation requirements for analytic methods. It may be used in children with nephrotic syndrome; however further studies are required to investigate focusing on sMPA and the correlation between sMPA and total MPA and its possible contribution to MPA TDM is required.

Rapid Detection of Amitriptyline in Dried Blood and Dried Saliva Samples with Surface-Enhanced Raman Spectroscopy

There is growing demand for rapid, nondestructive detection of trace-level bioactive molecules including medicines, toxins, biomolecules, and single cells, in a variety of disciplines. In recent years, surface-enhanced Raman scattering has been increasingly applied for such purposes, and this area of research is rapidly growing. Of particular interest is the detection of such compounds in dried saliva spots (DSS) and dried blood spots (DBS), often in medical scenarios, such as therapeutic drug monitoring (TDM) and disease diagnosis. Such samples are usually analyzed using hyphenated chromatography techniques, which are costly and time consuming. Here we present for the first time a surface-enhanced Raman spectroscopy protocol for the detection of the common antidepressant amitriptyline (AMT) on DBS and DSS using a test substrate modified with silver nanoparticles. The validated protocol is rapid and non-destructive, with a detection limit of 95 ppb, and linear range between 100 ppb and 1.75 ppm on the SERS substrate, which covers the therapeutic window of AMT in biological fluids.

Purinergic Signaling in Oral Tissues

The role of the purinergic signal has been extensively investigated in many tissues and related organs, including the central and peripheral nervous systems as well as the gastrointestinal, cardiovascular, respiratory, renal, and immune systems. Less attention has been paid to the influence of purines in the oral cavity, which is the first part of the digestive apparatus and also acts as the body’s first antimicrobial barrier. In this review, evidence is provided of the presence and possible physiological role of the purinergic system in the different structures forming the oral cavity including teeth, tongue, hard palate, and soft palate with their annexes such as taste buds, salivary glands, and nervous fibers innervating the oral structures. We also report findings on the involvement of the purinergic signal in pathological conditions affecting the oral apparatus such as Sjögren’s syndrome or following irradiation for the treatment of head and neck cancer, and the use of experimental drugs interfering with the purine system to improve bone healing after damage. Further investigations are required to translate the results obtained so far into the clinical setting in order to pave the way for a wider application of purine-based treatments in oral diseases.

Determination of Guanfacine in Oral Fluid and Serum of Children and Adolescents with Attention-Deficit/Hyperactivity Disorder: A Short Communication

BACKGROUND

Guanfacine, a selective α2A-adrenoreceptor agonist, is a second-line medication for treating children and adolescents with attention-deficit/hyperkinetic disorder. The dosage administered as milligram per body weight to balance the potential benefits and risks of treatment. Therapeutic drug monitoring (TDM) is useful for identifying a patient's therapeutic window to optimize individual drug dosing and reduce the risk of adverse drug reactions. However, in children and adolescents, intravenous sample collection is especially stressful and thus remains a primary challenge, restricting the use of TDM. Therefore, evaluating alternative specimens to facilitate TDM is a worthwhile task. The aim of this study was to assess the feasibility of using oral fluid for TDM of guanfacine in children and adolescents.

METHODS

In this article, 9 patients (median age 8.1 years; 6 boys and 3 girls) undergoing treatment with guanfacine were included. Simultaneously collected oral fluid and serum samples were deproteinized using methanol containing a stable isotope-labeled internal standard before the determination of guanfacine by liquid chromatography-tandem mass spectrometry. Pearson correlation and paired t test were used for statistical analysis.

RESULTS

The mean serum guanfacine concentration was 3 times higher than that detected in oral fluid (7.47 ng/mL versus 2.36 ng/mL; t (8) = 5.94; P < 0.001). A strong positive linear correlation (r = 0.758, P = 0.018) was identified between oral fluid and serum concentrations. A strong but nonsignificant negative correlation (r = -0.574, P = 0.106) was detected between the oral fluid pH and oral fluid-to-serum concentration ratio.

CONCLUSIONS

The strong correlation between oral fluid and serum concentration and the probable small effect of oral fluid pH on oral fluid-to-serum concentration ratio supports guanfacine as a suitable candidate for TDM in oral fluid.

Use of Saliva as an Alternative Matrix to Serum/Plasma for Therapeutic Drug Monitoring Using Reverse-Phase HPLC

PURPOSE

This study was conducted to examine and verify the use of saliva as an alternative matrix for monitoring phenytoin drug levels in patients with epilepsy. Drug concentrations are measured to evaluate whether a suitable drug level has been achieved to minimize the risk for toxicity, inadequate efficacy, or therapy resistance and compliance issues.

METHODS

Quantitative analysis was performed by using reverse-phase HPLC after sample pretreatment with acetonitrile. Seventy-eight patients who met the inclusion/exclusion criteria were examined in this study. Trough concentrations of both saliva and serum were taken at steady state.

FINDINGS

Of the 78 patients enrolled, only 11 (14.1%) had normal levels. Twenty-eight patients (35.9%) had subtherapeutic levels, and 39 (50%) had toxic levels. Simultaneously, salivary phenytoin levels were analyzed; only 13 patients (17.3%) had therapeutic levels, 25 patients (33.3%) had subtherapeutic levels, and 37 (49.3%) had toxic levels. Among the study population, most of the patients were aged 31 to 40 years (25.6%) followed by the age group 21 to 30 years (19.2%). The lowest percentage of patients were in the age groups 71 to 80 years and >80 years (1.3%) each. This study found a statistically significant relationship between free serum and salivary phenytoin levels (P < 0.001). A very weak and insignificant correlation was observed between serum/salivary phenytoin levels and sex/age of the study population. The results of the present study support the use of saliva as an alternative to serum/plasma for monitoring phenytoin therapy.

IMPLICATIONS

The free concentration of a drug represents the freely diffusible drug fraction, which is the therapeutically active form. Accordingly, the free drug concentration correlates to clinical efficacy and drug toxicity better than total concentration.

Relationship Between Amphetamine Concentrations in Saliva and Serum in Children and Adolescents With Attention-Deficit/Hyperactivity Disorder

BACKGROUND

Therapeutic drug monitoring (TDM) is a valid tool for the optimization of psychopharmacotherapy; however, in child and adolescent psychiatry, uncomfortable intravenous sample collection is the main challenge and restricts the use of TDM. Therefore, it is important to evaluate alternate specimens to facilitate TDM. The aim of this study was to evaluate the feasibility of using saliva for the TDM of amphetamine in children and adolescents with attention-deficit/hyperactivity disorder.

METHODS

In this study, 28 patient samples (mean age, 11.3 years; boys, 23; and girls, 5) treated with lisdexamfetamine were included. The active compound amphetamine was extracted and derivatized before quantification by high-performance liquid chromatography with fluorescence detection. Nonparametric Spearman rank correlations were used for correlation analyses; for clinical validation, Bland-Altman analysis was applied.

RESULTS

The median amphetamine concentrations in saliva were 2.7 times higher (range 0.7-23.6) than those in serum (257.8 ng/mL versus 77.2 ng/mL; z = -4.51, P < 0.001). A strong positive linear correlation was observed between saliva and serum concentrations (ρ = 0.628, P < 0.001). The ratio of saliva-to-serum concentration was strongly pH dependent (ρ = -0.712, P < 0.001). Therefore, a transformation formula, factoring in salivary pH, to calculate serum concentrations from the measured saliva concentrations was applied. Theoretical and measured serum amphetamine concentrations were subjected to Bland-Altman analysis. Using an acceptance limit of 20%, only 21% (n = 6) of samples fulfilled this criterion.

CONCLUSIONS

Amphetamine paired saliva-to-serum concentrations were highly variable and strongly affected by salivary pH, indicating that saliva is an inappropriate sampling matrix for TDM of amphetamine. Furthermore, Bland-Altman analysis did not support saliva as a suitable matrix for TDM.

Personalized Therapy for Mycophenolate: Consensus Report by the International Association of Therapeutic Drug Monitoring and Clinical Toxicology

ABSTRACT

When mycophenolic acid (MPA) was originally marketed for immunosuppressive therapy, fixed doses were recommended by the manufacturer. Awareness of the potential for a more personalized dosing has led to development of methods to estimate MPA area under the curve based on the measurement of drug concentrations in only a few samples. This approach is feasible in the clinical routine and has proven successful in terms of correlation with outcome. However, the search for superior correlates has continued, and numerous studies in search of biomarkers that could better predict the perfect dosage for the individual patient have been published. As it was considered timely for an updated and comprehensive presentation of consensus on the status for personalized treatment with MPA, this report was prepared following an initiative from members of the International Association of Therapeutic Drug Monitoring and Clinical Toxicology (IATDMCT). Topics included are the criteria for analytics, methods to estimate exposure including pharmacometrics, the potential influence of pharmacogenetics, development of biomarkers, and the practical aspects of implementation of target concentration intervention. For selected topics with sufficient evidence, such as the application of limited sampling strategies for MPA area under the curve, graded recommendations on target ranges are presented. To provide a comprehensive review, this report also includes updates on the status of potential biomarkers including those which may be promising but with a low level of evidence. In view of the fact that there are very few new immunosuppressive drugs under development for the transplant field, it is likely that MPA will continue to be prescribed on a large scale in the upcoming years. Discontinuation of therapy due to adverse effects is relatively common, increasing the risk for late rejections, which may contribute to graft loss. Therefore, the continued search for innovative methods to better personalize MPA dosage is warranted.

Emerging intraoral biosensors

Biomedical devices that involved continuous and real-time health-care monitoring have drawn much attention in modern medicine, of which skin electronics and implantable devices are widely investigated. Skin electronics are characterized for their non-invasive access to the physiological signals, and implantable devices are superior at the diagnosis and therapy integration. Despite the significant progress achieved, many gaps remain to be explored to provide a more comprehensive overview of human health. As the connecting point of the outer environment and human systems, the oral cavity contains many unique biomarkers that are absent in skin or inner organs, and hence, this could become a promising alternative locus for designing health-care monitoring devices. In this review, we outline the status of the oral cavity during the communication of the environment and human systems and compare the intraoral devices with skin electronics and implantable devices from the biophysical and biochemical aspects. We further summarize the established diagnosis database and technologies that could be adopted to design intraoral biosensors. Finally, the challenges and potential opportunities for intraoral biosensors are discussed. Intraoral biosensors could become an important complement for existing biomedical devices to constitute a more reliable health-care monitoring system.

Effects of Age, Drug Dose, and Sampling Time on Salivary Levels of Olanzapine, Quetiapine, and Their Metabolites

Although blood is the basic test material to monitor levels of antipsychotic drugs in a person’s system, saliva could serve as a more convenient test material. Therefore, the aim of this novel study was to determine the correlations between the salivary levels of olanzapine and quetiapine (and their metabolites: N-demethyl olanzapine and norquetiapine) and the patient’s sex and age, dose level, and the time of sampling. The study involved two groups of patients: 21 female patients starting treatment immediately after being admitted to the hospital and 36 male and female nursing home residents, long-time users of the studied drugs. Women had lower levels of the tested analytes than men. Quetiapine levels in the saliva of people starting the treatment showed a positive correlation with the age of the patients and a strong positive correlation with the dose level. The saliva levels of olanzapine showed a strong correlation with its metabolite in patients who had recently started treatment. Among long-time users of this drug, salivary levels differed significantly before and after administration. In conclusion, the results indicate that there is a possibility of using saliva as a material for monitoring quetiapine or olanzapine concentrations, especially in people starting treatment.

Potential of Oral Fluid as a Clinical Specimen for Compliance Monitoring of Psychopharmacotherapy

BACKGROUND

Oral fluid (OF) is being developed as a specimen for the determination of drug intake as an alternative to serum and plasma. It is generally considered as an attractive specimen due to the noninvasive nature of the sampling procedure and the relation to the free fraction of drug in the blood. These features are of particular value in drug treatment of psychiatric disorders. To establish OF for the purpose of monitoring drug therapy, the relationship between concentrations in OF and serum/plasma must be documented. This study explored one promising sampling device and comprised the following 10 drugs: aripiprazole, citalopram, duloxetine, escitalopram, mirtazapine, pipamperone, pregabalin, promethazine, quetiapine, and venlafaxine.

METHODS

For this purpose, 100 paired serum and OF samples were collected from patients undergoing pharmacotherapy and analyzed using a liquid chromatography-tandem mass spectrometry method. A commercial method from Chromsystems for the determination of these drugs in plasma was used and was adapted for OF and ultrafiltrated (Centrifree device) serum.

RESULTS

The ratio of each individual pair of samples was used to calculate a mean and SD value between OF and serum free and total concentrations. The OF concentration ratios to serum total fraction differed markedly between substances and differed from 10-fold lower to 8-fold higher. The ratios to serum free fractions were always higher. The relation between the OF and serum concentrations was also evaluated by regression analysis and determination of slopes and correlation coefficients. For all measured relations, there was a statistically significant relation between the OF and serum concentrations. The degree of drug protein binding was in agreement with literature. The aripiprazole, duloxetine, pipamperone, pregabalin, and promethazine concentrations in ultrafiltrated serum were not possible to measure because of low concentrations and nonspecific binding.

CONCLUSIONS

Despite a strong statistical correlation between OF and serum concentrations observed for most of the studied substances, it is still evident that OF concentrations cannot simply substitute serum/plasma as therapeutic drug monitoring specimen, but rather be considered as a unique specimen. We believe that OF is a promising matrix especially for compliance testing in psychiatry settings. The Greiner Bio-One device used in this study provides a sampling procedure that offers advantages over the available alternatives.

LC-MS-MS with Post-Column Reagent Addition for the Determination of Zolpidem and its Metabolite Zolpidem Phenyl-4-carboxylic Acid in Oral Fluid after a Single Dose

A rapid, selective and sensitive LC-MS-MS method with a post-column addition of acetonitrile was developed and fully validated for the quantitative determination of zolpidem and its major metabolite, zolpidem phenyl-4-carboxylic acid (ZPCA), in oral fluid. Preliminary sample treatment was limited to a simple dilution of 1 mL oral fluid specimen aliquots with methanol. Chromatography was performed on a Capcell Pak C18 MGII column (250 × 2.0 mm, 5 μm i.d., Shiseido, Tokyo, Japan) with isocratic elution using a water-acetonitrile mobile phase with 0.1% formic acid, 5% acetonitrile and 20 mM ammonium acetate in an aqueous phase at a flow rate of 0.4 mL/min. Acetonitrile was added post-column at a flow rate of 0.4 mL/min to enhance ionization of the analytes in the MS source. Detection was carried out on a QTrapTM 6500 mass spectrometer in positive ionization mode. Good linearities were generated over the range of 0.05-200 ng/mL for zolpidem and 0.1-200 ng/mL for ZPCA. Limit of detection for zolpidem and ZPCA were 0.01 ng/mL and 0.05 ng/mL, respectively, whereas LLOQs were 0.05 ng/mL and 0.1 ng/mL, respectively. This method meets the required criteria for bioanalytical analyses to be used for clinical and forensic purposes. Application of this method was demonstrated by testing authentic samples collected after a single oral dose to obtain insights into the general detectability and detection windows of zolpidem and ZPCA in oral fluid.

Could Salivary Cyclosporine Dosage Replace the Whole Blood Cyclosporine Measurements in Renal Transplant Patients?

Background:

Cyclosporin (CsA) has been extensively used as the immunosuppressant of choice in renal transplantation. Currently available approaches to assess CsA levels, both in serum and blood, fail to accurately reflect the concentration of the pharmacologically active drug fraction. Free CsA levels in biological fluids (blood or saliva) have been advocated to play an important role. Traditional salivary CsA monitoring tests are based on available archaic salivary techniques that are nonspecific and require large amounts of saliva. The aim of this study was to assess salivary CsA correlation using a novel and more accurate technique and to correlate with CsA levels in blood.

Material and Methods:

Patients provided blood samples of 2 ml and 2 ml of unstimulated saliva on the same day 2 h after the morning CsA dose (C₂). Whole blood levels of CsA were determined using the monoclonal fluorescent polarization immunoassay (FPIA) kit. The FPIA kit was adapted to salivary testing by using a novel extraction method developed and patented under the name of Middle East Research Institute (MERI). Wilcoxon signed rank test compared the differences in blood and salivary CsA. Pearson's correlation coefficient assessed the linear association between blood and salivary CsA concentrations. All analyses were performed using IBM-SPSS version 23 (IBM Corp, Armonk, NY, USA).

Results:

No significant correlation was observed between blood and salivary CsA levels.

Conclusion:

Salivary CsA concentrations at C₂ cannot adequately replace C₂ blood levels as an indicator of CsA bioavailability despite improved performance of monoclonal FPIA and application of the MERI technique. More studies may be warranted to design more reliable and less invasive procedures for therapeutic drug monitoring.

Design aspects of a case-control clinical investigation of the effect of HIV on oral and gastrointestinal soluble innate factors and microbes

INTRODUCTION

The impaired host defense system in HIV infection impacts the oral and gastrointestinal microbiota and associated opportunistic infections. Antiretroviral treatment is predicted to partially restore host defenses and decrease the oral manifestation of HIV/AIDS. Well-designed longitudinal studies are needed to better understand the interactions of soluble host defense proteins with bacteria and virus in HIV/AIDS. "Crosstalk" was designed as a longitudinal study of host responses along the gastrointestinal (GI) tract and interactions between defense molecules and bacteria in HIV infection and subsequent therapy.

PURPOSE

The clinical core formed the infrastructure for the study of the interactions between the proteome, microbiome and innate immune system. The core recruited and retained study subjects, scheduled visits, obtained demographic and medical data, assessed oral health status, collected samples, and guided analysis of the hypotheses. This manuscript presents a well-designed clinical core that may serve as a model for studies that combine clinical and laboratory data.

METHODS

Crosstalk was a case-control longitudinal clinical study an initial planned enrollment of 170 subjects. HIV+ antiretroviral naïve subjects were followed for 9 visits over 96 weeks and HIV uninfected subjects for 3 visits over 24 weeks. Clinical prevalence of oral mucosal lesions, dental caries and periodontal disease were assessed.

RESULTS

During the study, 116 subjects (47 HIV+, 69 HIV-) were enrolled. Cohorts of HIV+ and HIV- were demographically similar except for a larger proportion of women in the HIV- group. The most prevalent oral mucosal lesions were oral candidiasis and hairy leukoplakia in the HIV+ group.

DISCUSSION

The clinical core was essential to enable the links between clinical and laboratory data. The study aims to determine specific differences between oral and GI tissues that account for unique patterns of opportunistic infections and to delineate the differences in their susceptibility to infection by HIV and their responses post-HAART.

Trends in drug testing in oral fluid and hair as alternative matrices

The use of alternative matrices such as oral fluid and hair has increased in the past decades because of advances in analytical technology. However, there are still many issues that need to be resolved. Standardized protocols of sample pretreatment are needed to link the detected concentrations to final conclusions. The development of suitable proficiency testing schemes is required. Finally, interpretation issues such as link to effect, adulteration, detection markers and thresholds will hamper the vast use of these matrices. Today, several niche areas apply these matrices with success, such as drugs and driving for oral fluid and drug-facilitated crimes for hair. Once those issues are resolved, the number of applications will markedly grow in the future.

Continuous, quantitative monitoring of roxithromycin in human saliva by flow injection chemiluminescence analysis

Human saliva quantitative monitoring of roxithromycin (ROX) at picomolar-level by flow injection (FI) chemiluminescence (CL) analysis is described for the first time, to our knowledge. Monitoring was based on the CL intensity from luminol-BSA reaction, which can be quenched in the presence of ROX, with the decreasing CL intensity linearly proportional to the logarithm of the ROX concentration, ranging from 0.6 to 1000 pmol·L(-1). The detection limit of the proposed method for the determination of ROX was as low as 0.2 pmol·L(-1) (3σ), and the relative standard deviations were less than 4.0% (n = 7). A complete analytical process, including sampling and washing for ROX determination, conducted at a flow rate of 2.0 mL·min(-1), was performed completely within 30 s, yielding a sample efficiency of 120 h(-1). The proposed method was successfully applied to the determination of ROX in human saliva and serum samples with recoveries from 90.9% to 110.1%. The continuous monitoring of ROX in human saliva after oral intake showed that the total elimination ratio was 87.1% during 24 h, and the pharmacokinetic parameters were 0.97 ± 0.18 h(-1) for the absorption rate constant K(a), 0.082 ± 0.010 h(-1) for the elimination rate constant K(e), and 8.56 ± 1.11 h for the elimination half-life time t(1/2). It was also found that ROX in human saliva and urine simultaneously reached the maximum at 2 h with the concentration correlate ratio of 0.97.

Saliva as a diagnostic fluid

Salivary diagnostics is a dynamic and emerging field utilizing nanotechnology and molecular diagnostics to aid in the diagnosis of oral and systemic diseases. In this article the author critically reviews the latest advances using oral biomarkers for disease detection. The use of oral fluids is broadening perspectives in clinical diagnosis, disease monitoring, and decision making for patient care. Important elements determining the future possibilities and challenges in this field are also discussed.

Medication effects on salivary cortisol: tactics and strategy to minimize impact in behavioral and developmental science

The non-invasive measurement of cortisol in saliva has enabled behavioral scientists to explore the correlates and concomitants of the interaction between the activity of the hypothalamic-pituitary-adrenal (HPA) axis, intrinsic factors, and social forces as they occur naturally in everyday life. The widespread integration of salivary cortisol into behavioral science has also revealed that omnipresent features of everyday life such as, over-the-counter and prescription medications, have the capacity to influence measurement validity. We identify several pathways by which pharmacologic agents could influence salivary cortisol, including (a) direct agonistic and antagonistic effects on the HPA axis, (b) indirect effects on physiological systems networked with the HPA axis, (c) moderation or mediation effects on cortisol secretion via pharmacologically induced change in subjective experience, (d) iatrogenic effects on the availability or composition of saliva, or the diffusion of serum constituents into oral fluid, and (e) cross-reactivities with antibodies used to detect cortisol by immunoassay. Specific medications with the capacity to influence salivary cortisol via these pathways are documented in an effort to procedurally and statistically minimize this potential source of error variance in the next generation of studies.

Current technologies and considerations for drug bioanalysis in oral fluid

Drug oral fluid analysis was first used almost 30 years ago for the purpose of therapeutic drug monitoring. Since then, oral fluid bioanalysis has become more popular, mainly in the fields of pharmacokinetics, workplace drug testing, criminal justice, driving under the influence testing and therapeutic drug monitoring. In fact, oral fluid can provide a readily available and noninvasive medium, without any privacy loss by the examinee, which occurs, for instance, during the collection of urine samples. It is believed that drug concentrations in oral fluid may parallel those measured in blood. This feature makes oral fluid an alternative analytical specimen to blood, which assumes particular importance in roadside testing, the most published application of this sample. Great improvements in the development of accurate and reliable methods for sample collection, in situ detection devices (on-site drug detection kits), and highly sensitive and specific analytical methods for oral fluid testing of drugs have been observed in the last few years. However, without mass spectrometry-based analytical methods, such as liquid chromatography coupled to mass spectrometry (LC–MS) or tandem mass spectrometry (LC–MS/MS), the desired sensitivity would not be met, due to the low amounts of sample usually available for analysis. This review will discuss a series of published papers on the applicability of oral fluid in the field of analytical, clinical and forensic toxicology, with a special focus on its advantages and drawbacks over the normally used biological specimens and the main technological advances over the last decade, which have made oral fluid analysis of drugs possible.

Rapid saliva processing techniques for near real-time analysis of salivary steroids and protein

INTRODUCTION

Point-of-care (POC) measurements using saliva samples have immense potential to assess systemic health and wellbeing, but sample viscosity and contaminants can affect analyses. We sought a portable clean-up method for whole saliva appropriate for use with POC measurement techniques such as biosensors.

METHODS

Whole saliva from each of 13 male subjects was split into 5 fractions. Each fraction was treated with a different clean-up process: a freeze-thaw-centrifuge (FTC) step; centrifugation alone; or passage through a Mini-UniPrep polyethersulfone filter, cotton Salivette, or foam Oracol device. Following clean-up, each subject's treated saliva fractions were assayed for cortisol, testosterone, dehydroepiandrosterone (DHEA), and protein concentrations. The effects of clean-up methods on nonspecific binding (NSB) in a biosensor were also assessed.

RESULTS

Compared with FTC, no analytes were affected by centrifugation alone. Cotton Salivettes significantly altered all analytes, with increases in cortisol (+64%), testosterone (+126%), and DHEA (off-scale) levels, and decreased protein (-21%) and biosensor NSB (-75%). Oracol foam devices decreased DHEA levels by 28%. Mini-UniPrep filtration decreased testosterone (-45%) and DHEA (-66%) concentrations while increasing cortisol (+40%).

CONCLUSION

No method was optimal for all analytes, highlighting the need for validation of saliva treatment methods before their adoption in rapid POC analyses.